There are several reasons for the soreness in the arm after the blood draw: first, because the needle tip is relatively fine during the blood draw, there is a kind of damage to the epidermal nerve, thus producing the soreness in the arm, which usually does not require special treatment. Usually, after 24-48 hours of emotional relaxation, proper movement of the arm can be relieved; thirdly, superficial venous thrombosis may have formed in the blood vessel where the blood was drawn, resulting in local venous reflux obstruction and soreness of the arm, which can be ruled out by ultrasound to see if there is thrombosis, and if there is, certain anticoagulation treatment can be given.